A1.1 Planning, monitoring, adjusting
Grade 8 problems reward a process: plan a route before computing, monitor as you go (does this number make sense?), and adjust when it doesn't. The strategies: estimate first, track units, check with an inverse, and write the reasoning so you can find where it broke.
Example
Solve: A 250 mL bottle is 0.4 full. How much water is needed to fill it to 90%?
- Plan: find 90% of 250, subtract what is there.
- 90% of 250 = 225 mL; 0.4 × 250 = 100 mL; 225 − 100 = 125 mL.
- Monitor: 125 is half the bottle — plausible, since 0.9 − 0.4 = 0.5. ✓
Remember: The check is part of the answer, not an extra. A plausibility check catches most slips in seconds.